Respiratory mask



FIG. 1 is a front perspective view of a respiratory mask according to an embodiment of my/our design;

FIG. 2 is a reverse perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view thereof; and,

FIG. 6 is a right side view thereof, with the left side view being a mirror image.

Where included, broken lines showing environment or structure are for illustrative purposes and form no part of the claimed design.

Where included, dotted lines indicate the border between claimed and unclaimed subject matter and form no part of the claimed design. 

The ornamental design for a respiratory mask, as shown and described. 